Don't you know the difference between the startup of an application container (which takes 3-4 seconds) and a page refresh which depends on what your application is doing?
There are a lot of companies using Spring, at least in Europe I can't count them. I don't know on what planet you're living :)
Java and spring are everywhere. I think you'd be (unpleasantly?) surprised just how often you're using websites that are running on top of Java and you just didn't know it.
The list just goes on and on. It's fast (okay maybe not as fast as carefully hand-rolled C++, but used the right way it can get near to it), has lots of mature tooling, and most importantly of all is absurdly stable.
If you're worried about start up time, you're likely worrying about the wrong thing. Amazon, for example, is well known to scale up and down their infrastructure on demand, and yet they're running on Java. They wouldn't do that if application start-up time was a problem.
It's rare to see java applications that take more than 5-10 seconds to start up unless they're insanely monolithic and pulling in large numbers of libraries (aka enterprise stacks like Websphere), and once they're running you leave them running.
Java start up time should be the shortest part of the whole 'spin up a new instance and start handling requests'.
There are a lot of companies using Spring, at least in Europe I can't count them. I don't know on what planet you're living :)